Fix identification of JS default params.

Author: sjrd

compiler/src/dotty/tools/dotc/transform/sjs/JSSymUtils.scala

@@ -99,17 +99,13 @@ object JSSymUtils {
     def isJSDefaultParam(using Context): Boolean = {
       sym.name.is(DefaultGetterName) && {
         val owner = sym.owner
-        if (owner.is(ModuleClass)) {
-          val isConstructor = sym.name match {
-            case DefaultGetterName(methName, _) => methName == nme.CONSTRUCTOR
-            case _ => false
-          }
-          if (isConstructor)
-            owner.linkedClass.isJSType
-          else
-            owner.isJSType
+        val methName = sym.name.exclude(DefaultGetterName)
+        if (methName == nme.CONSTRUCTOR) {
+          owner.linkedClass.isJSType
         } else {
-          owner.isJSType
+          def isAttachedMethodExposed: Boolean =
+            owner.info.decl(methName).hasAltWith(_.symbol.isJSExposed)
+          owner.isJSType && (!owner.isNonNativeJSClass || isAttachedMethodExposed)
         }
       }
     }